Certain embodiments of the present invention generally relate to connectors that electrically connect circuit boards to one another and more particularly relate to electrical contacts that join differential pairs of signal traces on first and second electrical wafers orthogonally aligned with one another.
Various electronic systems, such as computers, comprise a wide array of components mounted on printed circuit boards, such as daughterboards, backplanes, motherboards, and the like which are interconnected to transfer signals and power throughout the systems. The transfer of signals and power between the circuit boards or electrical wafers requires electrical connectors between the printed circuit boards. The printed circuit boards may be aligned at various angles to one another (hereafter collectively referred to as orthogonal). Typical connector assemblies include a plug connector and a receptacle connector. Each plug and receptacle connector may house a plurality of electrical wafers. An electrical wafer may be a thin printed circuit board or a series of laminated contacts within a plastic insulator. The electrical wafers within one connector may be mated along an edge with the electrical wafers in the other connector in an orthogonal manner.
Conventional electrical connectors for orthogonally aligned electrical wafers include ground contacts and signal contacts. Each electrical wafer has contact pads along a mating edge and along a base edge. Each ground contact engages one ground contact pad on one side of a horizontal wafer along the mating edge and two ground contact pads on opposite sides of a vertical electrical wafer. Likewise, each signal contact engages one signal contact pad on one side of a horizontal wafer (opposite the signal contact pad) and two signal contact pads on opposite sides of a vertical electrical wafer. A single trace extends from each contact pad along the mating edge of the horizontal wafer to a corresponding contact pad along the base edge. Similarly a single trace extends from each opposite pair of contact pads along the mating edge of the vertical wafer to a corresponding contact pad along the base edge. The contact pads along the base edge of both the horizontal and vertical wafers are in turn connected to contact pads on the printed circuit boards attached to both connectors, thus creating an electrical path between the printed circuit boards.
However, conventional electrical connectors for orthogonally aligned printed circuit boards only carry traces configured for single ended applications. Hence, each individual trace on the wafers is treated as an independent signal path that is preferably electromagnetically isolated from other traces on the wafers. Today, printed circuit boards are being used to carry signals arranged in differential pairs as well. Consequently, it would be advantageous for an orthogonal electrical connector to maintain the signals in a differential pair arrangement. Thus, there is a need for electrical connectors that convey differential pair signals across orthogonal wafers from one printed circuit board to another printed circuit board.
In accordance with certain embodiments of the present invention, an electrical connector assembly is provided that includes a plurality of wafers having ground and signal traces with the signal traces being arranged in differential pairs. The electrical connector assembly includes a first connector housing that has channels adapted to retain a first group of wafers, and a second connector housing that has channels adapted to retain a second group of wafers. The electrical connector assembly also includes signal contacts joining the differential pairs of the signal traces on the first group of wafers with corresponding differential pairs of the signal traces on the second group of wafers. The first and second connector housings join the first group of wafers in a non-parallel relationship to the second group of wafers.
In certain other embodiments, an electrical connector assembly includes a plurality of wafers having ground and signal traces with the signal traces being arranged in differential pairs. The electrical connector assembly includes a first connector housing that has channels adapted to retain a first group of wafers, and a second connector housing that has channels adapted to retain a second group of wafers. The electrical connector assembly also includes a wafer interface with cavities and ground and signal contacts loaded into the cavities. The signal contacts are arranged in differential pairs and with corresponding ground contacts located therebetween along a first axis. Each ground contact and signal contact has ground beams and signal beams, respectively. Each ground beam is located immediately adjacent and facing a corresponding signal beam. The wafer interface holds the signal beams in a biased state to deflect the signal beams away from corresponding ground beams to define gaps therebetween.